<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* a link{
            color: blue;
        }
        a:hover{  
            color: red;
        }
        a:active{
            color: green;
        } */
        /* a:visited {
            color: blue;
        } */
        /* input {
            color:aqua;
        }
        input:hover {
            color: red;
        }
        input:active {
            color: blueviolet;
        } */
        .three>input:focus{
            color: rgb(0, 60, 255);
        }
    </style>
</head>
<body>
    <div class="three">
        <input type="text">
        <input type="text">
        <input type="text">
        <input type="text">
      </div>
     <!-- <a href="https://www.w3school.com.cn/css/css_selector_id.asp">不跳转</a>
     <br>
     <input type="button" value="按钮"> -->
</body>
</html>